Electrophysiologic study of the heart: A test of the electrical conduction system of the heart (the system that generates the heart beat).

Electrophysiologic study (EPS) of the heart is done by threading thin plastic tubes (catheters) into a vein where the leg connects to the abdomen. A local anesthetic is given as well as a mild sedative. The procedure is not painful and the patient is not put to sleep. After being placed into the vein, the catheters are then passed under fluoroscopic guidance into the heart. These catheters measure the electrical signals generated by the heart. They can a much more detailed analysis of these signals than a simple electrocardiogram (ECG). The catheters are used to rapidly pace the heart -- to make the heart beat quickly. The electrical conduction system of the heart is also measured during this rapid pacing and the heart is observed to see if any abnormal heart rhythms develop.

The reason for doing EPS may to determine:

• If a person needs a pacemaker. (This can usually be decided without an EPS but once in a while EPS is necessary.)
• Why a person is fainting (if other tests to find a basis have failed to find one).
• If a person is prone to a fast heart rhythm (tachycardia) and guide the appropriate treatment for this abnormal heart rhythm (arrhythmia).
• Whether past treatment for a fast heart rhythm has been satisfactory.